This invention relates to method and apparatus for automatic operation of a container crane of a type for loading and unloading a cargo, especially, containers carried on a ship, or more in particular to method and apparatus for automatic operation of a container crane with a container storage area thereon for automating cargo conveyance between the storage area which is used as the container handling origin and the ship, i.e., the ship-side conveyance, and cargo conveyance between the storage area and the transportation equipment prepared at the rear of the crane, i.e., the land-side conveyance.
In the operation for loading and unloading cargo containers onto and from a ship moored to the quay of a port, cargo conveyance between the container ship and the quay has been effected with a container crane provided on the quay, while the conveyance between the quay and a container yard at the rear thereof has been carried out by suitable transport equipment such as a straddle carrier, truck or yard crane.
In unloading a container from a container ship, for example, the container crane is operated in such a cycle that it first lifts the container vertically upward from the container ship, moves it horizontally in the direction at the right angle to the quay side and then brings it down on the quay. In the case where the conveyance cycle of the transport equipment at the rear of the crane fails to conform to that of the container crane, the container lifted by the container crane must be temporarily stored on the quay at an area not to interfere with the operation of the rear transport equipment. This adds to the work for conveyance of the container to the work for storage on the quay. If the container crane is operated in such a manner that the operation cycle of the container crane conforms to that of the rear transport equipment, by contrast, the operating efficiency of the container crane is reduced, resulting in the failure of the container crane to effect its full capacity to handle the cargo.
In order to overcome these disadvantages and improve the operating efficiency of the container crane, various types of container crane systems have been suggested which comprise a container crane with a storage area thereon for temporarily storing containers and an auxiliary spreader for conveyance of the containers between the storage area and the transport equipment prepared at the rear of the container crane. One of such types of container crane is disclosed in the Journal of ICHCA Cargo System, pages 13 and 18, issued May, 1976 as well as in U.S. Pat. No. 3,812,987 issued May 28, 1974 on U.S. application Ser. No. 193,276 filed Oct. 28, 1971. Such types of container crane, as described above, have a storage area thereon for storing containers. The location of this storage area is used as a cardinal point in the control of the system for carrying out the ship-side operation between the container ship and the storage area of the container crane and the land-side operation between the storage area and the transport equipment independently of each other. This not only reduces the time required for one operation cycle of the container crane but also improves the operating efficiency thereof.
This type of crane has separate control cabs for the ship-side and land-side cargo handling operations. The operators in these control cabs carry out the ship-side and land-side cargo operations separately. The ship-side cargo handling operation, for example, requires six to eight stevedores on board in addition to the operator in the control cab relates to main spreader. The operator, by manual operation, places the spreader in position in the vicinity of a target point of the cargo handled, and then the stevedores correct the spreader position. After that, the crane operator operates, with aid of the stevedore's sign, to locate the spreader exactly in position for container handling operation. The land-side operation is also accompanied by several helpers working in the transport equipment prepared at the rear of the crane, so that with the aid of helpers signals the crane operator of auxiliary spreader operates the crane to perform the cargo-handling operation.
The cargo-handling operation by the container crane in the above-mentioned system requires high skill of the crane operators. Further, the requirement of additional helpers (or stevedores) poses a safety problem. The most serious problem, however, is that the requirement of the work by helpers (or stevedores) increases the cargo-handling time and hence additional demurrage, thereby reducing the efficiency of cargo-handling operation.
An object of the present invention is to provide a method and an apparatus for automatic operation of a container crane, which is capable of automatically performing the ship-side and land-side cargo-handling operations of the container crane.
Another object of the invention is to provide a method and an apparatus for efficient and safe automatic operation of a container crane at low cost of the ship-side and land-side operation of the container crane.
The objects of the present invention are achieved by a container crane system comprising a crane with a container storage area thereon, a main spreader for performing the ship-side cargo-handling operation between the storage area and a container ship having a hatch into which the container is transported along a cell guide, and an auxiliary spreader capable of performing the land-side cargo-handling operation between the storage area and the transport equipment prepared at the rear of the crane by controlling the same in such a manner that in ship-side operation, the main spreader is first subjected to teaching operation with respect to desired points on and within the hatch to determine the positions of the ship and the crane relative to the ship-side end of the storage, then storing in memory the ship and the crane relative positions. In subsequent cargo-handling processes, the information thus stored, together with the geometric relation of container-loading positions determined by the ship structure, displacement of relative positions of the ship and the container crane, the state conditions of the main spreader and the crane, and the like, are used to calculate a target operation point for the main spreader. Then, the main spreader is operated through corrective playback control by which the spreader position is automatically corrected in accordance with the information thus obtained, while in the land-side cargo-handling operation, on the other hand, the travel schedules between the land-side end of the storage area and the transport equipment located at the rear of the crane are programmed, so that an auxiliary spreader is automatically operated in accordance with the program.